With Donald Trump the clear front-runner in the Republican presidential primary, The Washington Post's Chris Cillizza says these are the five people the business mogul might pick as his running mate if he clinches the nomination. (Sarah Parnass/The Washington Post)

Update: Ted Cruz's exit from the race on Tuesday night means speculation about Trump's vice presidential pick will pick up. Here's our initial rundown of five people who could be the pick, from Friday. This post has been updated.

Donald Trump's victories in a series of Northeastern and Mid-Atlantic states over the past two weeks, culminating in his big win Tuesday in Indiana and Ted Cruz's exit, have made one thing clear: He is the presumptive Republican nominee.

Sen. Ted Cruz (R-Tex.) suspended his presidential campaign May 3 after suffering a stinging loss in the Indiana primary to Republican presidential front-runner Donald Trump. (Reuters)

Even the RNC now says so.

Which raises the question: Who is he going to pick as his vice presidential nominee?

The short answer: No one knows. Trump relishes being unpredictable, so trying to game out how this most unconventional of politicians will make his mind up is a bit of a guessing game. Add to that the fact that Trump's inner circle remains, largely, devoid of establishment types, and you quickly get into a situation where the people talking don't know much and the people who do know aren't talking.

Trump himself has been open about the lack of thought he has put into the process. "I just don't want to think about it right now," he said of the veepstakes following his five-state sweep on Tuesday night.

That's never stopped me before, though -- and it won't stop me now! Below the five people most likely to wind up as Trump's second-in-command, ranked in the order of likelihood. Caveat: These rankings can and will change. (Check out Hillary Clinton's VP rankings here.)

5. Marco Rubio: Yes, there was that whole "Little Marco" thing. But if Ben Carson can make peace with Trump, then anything can happen. Rubio is clearly in search of a next step in his political career, and while most insiders raise questions about whether he would accept the vice-presidential nomination, it's still hard for me to imagine anyone turning it down. Rubio could help Trump with outreach to establishment Republicans and in Florida. As a Cuban American, he also might be able to blunt some of Trump's sharpest edges on immigration and avoid an electoral disaster in the Hispanic community.


4. John Kasich: Trump has gone on offense against "1-for-41 Kasich" of late, but in general, these two have been on (relatively) friendly terms throughout the race. Kasich would represent an olive branch -- of sorts -- from Trump to the establishment and might carry the sort of résumé (member of Congress, Midwestern governor) that would appeal to Trump. And Kasich, who is in the middle of his second term, might find the chance at a vice-presidential nomination -- even if it meant sharing a ticket with Trump -- impossible to resist.

3. Joni Ernst: The Republican senator from Iowa emerged as a breakout star of the 2014 midterm election with her plain-spoken populism. Ernst, like many female Republican politicians, has been critical of Trump's comments about women, which could either appeal to him or disqualify Ernst entirely. If Trump wanted to make a turning-over-a-new-leaf pick, Ernst would make a ton of sense. If Trump believes "being Trump" is the essence of his appeal, he might look askance at anyone who has crossed him. Ernst has proven she is a gifted communicator and someone who might help sell Trump to the Midwestern voter he badly needs if he wants to be competitive with Clinton.

2. Rick Scott: The Florida governor wrote a Facebook post Wednesday urging the party to rally behind Trump. "The Republican leaders in Washington did not choose him, but the Republican voters across America did choose him," Scott wrote. "The voters have spoken." Scott has been consistently supportive of Trump for months now, endorsing him as soon as the real estate billionaire won the Sunshine State in early March. Scott's profile is also likely appealing to Trump -- a wealthy businessman who ran and beat the Republican establishment to get elected governor. Plus, he's from a big swing state.

1. Chris Christie: "I think Chris Christie is fantastic," Trump said Tuesday night as the New Jersey governor (and his wife) stood just behind him onstage. No one has risked more with his support for Trump than Christie, who has been roundly mocked and dismissed by the GOP establishment for the decision. Personality-wise, Christie and Trump seem to be an obvious match. And Trump has said before that he would want a politician as his running mate. From a geographic/ideological standpoint, Christie doesn't add a ton to the Trump ticket. But who knows if Trump even cares?